This invention relates to a system for spectrometry which includes a spectrophotometer and in particular to a control unit for processing the data obtained by the spectrophotometer.
Many of the currently used systems for spectrometry comprise a spectrophotometer and a control unit which are provided as two separate components. The spectrophotometer is a hardware instrument for spectrophotometry and includes a light source, a spectroscope, a sample stage (or a sample holder) and a photo-detector. The control unit is for controlling the operation of the spectrophotometer and processing output signals from the spectrophotometer. The recent trend is to form a control unit with a variety of functions by running control programs for spectrometry on a multi-purpose personal computer.
The functions of such a control unit include the following. Before a measurement, a user interface is provided through which the user is required to select and set parameters related to the measurement such as the wavelength and the method of measurement (such as the point measurement and the scan measurement) and signals corresponding to such parameters are transmitted to the spectrophotometer. During the measurement, the control unit controls the operations of the individual parts of the spectrophotometer according to a specified time schedule, collects the output signals from the spectrophotometer and stores in a memory device data obtained therefrom. After the measurement, the data obtained by the measurement are processed in order to calculate the transmissivity and the absorptivity of the sample and the results of such calculations are outputted through an output device such as a display or a printer.
A system for spectrometry can be used not only for investigating the absorption characteristics of a sample in analytical chemistry but also in a variety of other fields. In the production of optical filters, for example, it is necessary to measure the transrnissivity of the produced filters to check whether they indeed have the predetermined value or below and a system for spectrometry can be used for such a test. In a research in biochemistry, as another example, a system for spectrometry may be used for measuring the concentration of a specified component. If the absorptivity of a certain sample is known at wavelengths 260 nm and 230 nm, for example, the concentrations of nucleic acids (such as DNA and RNA) and protein contained in the sample can be obtained by carrying out a certain calculation using these values.
Prior art control units of a system for spectrometry have the function of outputting the transmissivity and absorptivity at a specified target wavelength to an output device but are not provided with the function of carrying out calculations or making judgments by using values of transmissivity or absorptivity. In order to carry out such calculations or to make judgments, therefore, the user had to himself/herself carry out calculations or make judgments on the basis of the results of measurements outputted to the output device or to prepare a program for processing the results of measurements and to carry out the troublesome task of transferring the data on the results of measurements from the control program for spectrometry to this prepared program.
It is therefore an object of this invention, in view of the problem described above, to provide an improved system for spectrometry having the function of carrying out calculations by using measured values such as transmissivity and absorptivity obtained as a result of spectrometry.
It is also an object of this invention to provide a method for spectrometry having such function.
A system for spectrometry embodying this invention, with which the above and other objects can be accomplished, may be characterized not only as comprising an input device, a measuring device with a spectrophotometer to obtain measured values, a calculating device and an output device for outputting results of calculations by the calculating device but also wherein the input device allows a user to input target wavelengths at which spectrometric measurements are to be carried out, character arrays representing variables assigned to measured values which are to be stored, and character arrays representing calculation formulas created according to specified rules and the calculating device analyzes the character arrays representing the calculating formulas and carries out calculations of the calculating formulas by replacing any of the character arrays representing the variables, if contained in the calculating formulas, each by corresponding one of the measured values.
A control unit having various functions for spectrometry for such a system according to this invention may be formed, for example, by installing a multi-purpose operating system (OS) into a personal compute equipped with an input device (such as a keyboard or a mouse), a display device (such as a CRT or an LCD), a central processing unit (CPU) and memory devices (such as ROM, RAM and HDD) and running a specified program on this operating system. This control unit serves to display formula-generating screens (such as the screens for generating calculation formulas and judgment formulas) on the display device when the user carries out a certain operation on the input device. It is on such screens that the user inputs through the input device not only the target wavelength at which spectrometry is to be carried out but also the names of the variables where measured values (say, of absorptivity and transmissivity) at this target wavelength are to be stored. In addition, the user generates formulas for calculations from the input device according to certain rules and registers these formulas in the system. In general, the formulas (or expressions) for calculations are formed by using elements including calculation operators (arithmetic operators +, xe2x88x92, * and /), comparison operators ( greater than ,  less than , =, etc.), logical operators (and, |, !=, AND, OR, NOT, etc.), character arrays indicating constants and variables defined by the user, character arrays representing constants and variables installed in the system, and numerical values expressed by Arabic numerals.
After a target wavelength, variable names and operation expressions are inputted, the user sets a sample at a specified position in the system and inputs an execute command for starting spectrometry. When this command is received, the system carries out the measurement of the sample by means of the spectrophotometer of its measuring device and obtains measured values at the specified target wavelength. After the measured values are obtained, the calculating means of the system carries out calculations by analyzing the earlier inputted character arrays in the operation expressions. In this operation, the calculations are done by replacing the variable names contained in the character arrays of the operation expressions by measured values which have been obtained. After a result of calculation is obtained, the output means of the system outputs it in a form recognizable by the user.